One or the other-- 400M crank or 351W has a shoulder just forward of the #1 main, the other doesn't. That's the only sticking point. Clearancing the block, longer rods and shorter pin height pistons are a must for any stroker project. BroncoRoadKill is also correct about the price. Once you do the machinework and buy pistons and reconditioned rods, you've probably spent what a stroker kit goes for. My 331 short block cost me $1500, including the cam. Block was $50 from a local machine shop (the PO abandoned it there) stroker kit, boring, clearancing was $1225, cam was $115. Throw in the oilpump, main girdle and timing set and it added up to around $1500.